Hair and nails, like the outer layers of skin, are made of dead cells that grow from a living base. The dead parts that show above the skin’s surface can be cut or damaged without causing pain, but damage to the living roots is painful. The condition of the hair and nails often reflects general health. Changes in the nails, in particular, may indicate an underlying disease.
Most hair and nail disorders are not a health threat but may be unsightly and cause embarrassment. However, some are caused by serious health problems. For example, excessive growth of body hair may be due to a hormonal imbalance, and spoon-shaped nails suggest iron deficiency. In these cases, treating the underlying disorder often improves the condition. Hair disorders may be due to factors such as drug treatments and localized skin diseases. Many nail abnormalities are usually due to minor injury or infection but they can be difficult to treat because topical preparations do not penetrate the nail. A damaged nail will not appear normal until it grows out, so the condition of the nails is sometimes an indication of past rather than present health.
This section begins by describing several disorders that affect scalp or body hair. The remaining articles describe abnormalities of the nails and the skin that surrounds them. Some common scalp problems are discussed elsewhere, including head lice and seborrhoeic dermatitis.
For more information on the structure and function of hair and nails, see Skin and Hair.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.